Combination refrigeration and evaporating cooling unit



Feb. 17, 1953 s FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT Filed April 8,1952 5 Sheets-Sheet l Arch/e S. Fe/nberg INVENTOR.

A TTORNEY Feb. 17, 1953 A. s. FEINBERG COMBINATION REFRIGERATION ANDEVAPORATING COOLING UNIT Filed April 8, 1952 5 SheetsShet 2 Arch/e S.Fe/nberg INVENTOR.

A TTORNEY Feb. 17, 1953 A. s. FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT 5 Sheets-Sheet 3Filed April 8, 1952 Archie 5. Feinberg I INVENTOR.

ATTORNEY 2: &

uni x22 30 6 Feb. 17, 1953 A. s. FEINBERG 2,628,480

COMBINATION REFRIGERATION AND EVAPORATING COOLING UNIT Filed April 8,1952 5 Sheets-Sheet 4 I/PcH/E 6. FE/NBE/Pa INVENTOR.

Feb. 17, 1953 A. s. FEINBERG COMBINATION REFRIGERATION AND EVAPORATI NGCOOLING UNIT Filed April 8, 1952 5 Sheets-Sheet 5 III . FE/NBERG'INVENTOR.

ATTORNEY Patented Feb. 17, 1953 UNITED COMBINATION REFRIGERATION ANDEVAPORATIN G COOLING UNIT Archie S. Feinberg Dallas, Tex.

. Application Aprira aszfs riaiN .2 s1,122

2 33'Claims.

This invention relates to air conditioningapparatus and moreparticularlyto, such apparatus employing both refrigerating andevaporative cooling systems.

This application is a continuation-in-part of my co-pending applicationSerial No. 145,833, filed February 23, 1950, now'abandoned.

The normal summer temperatures in the northern half of the United Statesseldom exceed 85 degrees Fahrenheit but the relative humidity of theatmosphere is usually relatively high. Refrigerating systems for airconditioning rooms and buildings are largely employed in this northernhalf of the United States because of the ability of these systems todehumidify as well as to cool the treated air. Refrigerating systems,however, are costly to operate since large amounts of power are neededto compress and liquefy the refrigerant gas employed in these systems.Prolonged periods of compressor operation are made necessary even duringperiods when the outdoor atmospheric temperature is as low as '78 to 79degrees Fahrenheit by the increase in temperature of the air in the airconditioned space due to the heat released in the air conditioned spaceby human occupants and lights and other heat emitting appliances. Thishuman occupancy heat load, as it is termed in the industry, necessitatesoperation of the compressor even though the outdoor atmospherictemperature and relative humidity conditions may be such as to beentirely comfortable to human beings. Human occupancy of the airconditioned space not only raises the temperature of the air within theair conditioned space but also raises the relative humidity since watervapor is released by the human occupants through perspiration thusincreasing their discomfort. The operation of a refrigeration system isuneconomical during periods when the outdoor atmospheric conditions arecomfortable to human beings. The human occupancy heat load can be moreeconomically removed by moving fresh air from the outdoors into the airconditioned space and expelling outdoors the air which has been heatedand humidiv fied by the human occupants of the space. The temperature ofthe outdoor air may have to be lowered a relatively small degree toallow for the gradual warming of the air in its passage through (Glitz-1)- the outdoorair can be accomplished very-fecoi the air conditionedspace due to the heat emitted a predetermined value. This small coolingof nomi'cally by evaporative cooling. v

Control of the temperature and humidity in the conditioned space byevaporative coolingand continuous exchange of air within the airconditioned space is feasible only during periods-- when the dry bulbtemperature of the outside air is about 86 degrees Fahrenheit or lessand the wet bulb temperature is about '79 degrees Fahrenheit or less.When these atmospheric conditions do not obtain a refrigerating systemis needed to cool the air within the air conditioned space. It isdesirable, therefore, for economical and satisfactory operation of anair conditioning apparatus that it provide a refrigerating system foruse when outdoor temperatures are above degrees Fahrenheit and anevaporative'cooling system for use when outdoor temperatures are 8 5degrees or lower. By using air conditioning sys-j tems having bothsystems, the periods of costly. operation of the refrigerating system,are greatly reduced since itop'erates only during'the rela-' tively fewand short periods when the dry bulb". temperature of the outdoor airexceeds 85 de-' grees Fahrenheit or the wet bulb temperature exceeds 79'degrees Fahrenheit. The air condi' tioning apparatus must also becapable of con'-. tinuously displacing a greater volume of air duringthe time the evaporative cooling system is in operation than isnecesasry during the time the refrigerating system is in operation.More-. over, in order to meet the needs of varying internal and externalconditions the controls of. the air conditioning apparatus shouldprovide for automatic changeover from operation of one sys-l. tem'tooperation of the other system upon a 'pre determined change in internaland external 'con-' ditions as well as for selective choice of operation of either system. I i

Accordingly, 'it is an object of myin-vention to provide a new andimproved air conditioning apparatus. 1

It is another object of my invention to provide a new and improved airconditioning apparatus having a refrigerating system for conditioningair when the outdoor air temperature exceeds a predetermined value andan evaporative cooling system for conditioning air when the outdoor temperature is less than a predetermined value. 7

It is another object of my invention to provide a new and improved airconditioning apparatus having a refrigerating system including an evaporative condenser provided with a blower'and water spray system andhaving an evaporative cooling system employing the blower and waterspray system of the evaporative condenser of the refrigerating system.

It is another object of my invention to provide a new and improved airconditioning apparatus having a refrigerating system, and an evaporativecooling system, and being provided with means for automaticallyoperating the refrigerating systemwhen. the outdoor ,air.---tem-.

perature exceeds a predetermined. value and for automatically operatingthe evaporative cooling system when the temperature falls below a pre-.:

determined value.

It is another object of my invention ta-prof vide a new and improved airconditioning apparatus provided with a refrigerating system and anevaporative cooling system and .withlcontrols for automatic changeoverfrom operationof one sys tem to operation of the other system upon,pre-;determined changes in internal and external conditions".

It is still another. object .of, my invention to providea new andimproved air conditioning apparatusprovided witha refrigerating systemand.

anevaporative cooling system and with controls foriselective choice ofoperation of either system.

It .isanother object of the invention to provide a new and improved airconditioning appa l ratus having. a refrigerating system forconditioning.,.air when. the outdoor temperature ex-i ceedsaprede'terminedwalue and a system for increasing. the volume of flow ofair from the outdoor atmosphere when the outdoor temperature isless thanthe predetermined value.

Briefly stated, my new and improved air conditioning apparatus.comprises a refrigerating system..and an evaporative cooling system. Therefrigeratin system is provided with a compressor ,.for,..compressingarefrigerant, gas. an evaporative condenser .coil in which the,compressed gas is.coole d and liquefied, a ,spraysystem for cooling theevaporative condenser coil by. spraying Water on ..th.e..coi1,acondenserblower for, moving air past the evaporative condenser coil andremoving totheoutdoors the. heat released bythe refrig erant gasjncooling and liquefyingthe refrigerant, a coolingrcoil in which theliquefied gas is allowed to evaporate and expand, and aconditionerblower for moving recirculated and fresh outdoor air past thecooling coil to be cooled and dehumidified by the absorption of heat bythe refrigerant gas and into the air conditioned space. The evaporativecooling system employs the spray system and the condenser blowerassociated with the evaporative condenser coil and includes a duct tomove air cooled by evaporation of the spray to the conditioned air spaceand a damper which selectively directs the flow of the, air past thespray-to the air conditioned space or to. the'oute doors. In operationthe refrigerating system is employed when the outdoor temperatureexceedsa predetermined value and the damper is positioned to direct the airmoved past the spray to the outdoors. The only air entering the airconditioned space is moved past the cooling coil by theconditioner-blower; The latterair may be partly recirculated air or maybe wholly fresh air moved from the outdoors;

During this period the compressor operates as needed. When thetemperature falls below a predeterminedvalue, the compressor ismaintained inoperative but the conditioner blower remains in operationto move air from the outdoors into the air conditionedspace. Thecondenser blower associated with'the evaporative condenser coil is also"maintained inoperation and moves air'from the outdoors through thewater spray where its temperature is lowered by evaporative cooling andinto the air conditioned space, the damper being moved to direct theflow of air from the outdoors to the air conditioned space. During theoperation of the evaporative cooling system all blowers may move airfrom the outdoors and into the air conditioned space, moving. a greatvolume of air throughthe air conditioned room to remove the humanoccupancy emitted heat. Only a portion of the air is cooled since theair moved by the cooling coil blowers is not cooled, the compressorbeing inactive. Controls are provided for automatically controlling theoperation of all dampers, compressors, and motors of the air con-"ditioning apparatus to insure that the refrigerating system operateswhen th temperature of the, outdoor air exceeds a predetermined valueand that the evaporative cooling system operates when the temperaturefalls below a predetermined value.-

Ina modified iormof the invention,- all of theair -moved by theconditioner blower is drawnfrom the conditioned space. In this case, theinflow-of outdoor air through doors or windows into the conditionedspace is relied upon to provide the proper proportion of. fresh air torecir'-. culated air during normal operation of the refrigeratingsystem. When-the outdoor temperature does not 'exceed the predeterminedValue;- the condenser blower'is employed, as in the first;

described embodiment, to increase the 'rate of flow of outdoor air intothe conditioned'space;

Fora better understanding of my invention,- reference maybe had to thefollowing description taken in connection with the accompanying drawing,and itsscope Will be pointed out in the. appended claims.

In the drawingr;

Figure 1 is a schematic diagramofthe air conditioningapparatus:- withall electric circuits omitted;

Figure 2 is a diagrammatic perspective of the air, conditioningapparatus of Figure '1 installed for operation and with all electriccircuits omitted;

Figure 3 is a diagrammatic illustration of the control circuits of theair conditioning apparatus of Figures 1 and 2; and,

Figure 4 is a schematic diagram of a modified form of the airconditioning apparatus; and,

Figure 5 is a perspective view'of a building; with the top removed andsome walls broken away; provided with another modified form of the airconditioning apparatus.

Referring nowespecially to Figure l, the prine ciple .of operation of apreferred embodiment of my invention is disclosed as employed tomaintain comfortable temperature and humidity. C011! ditions in theconditioned space i 0 which may be a room, a series of rooms, or anentire building. The air conditioningapparatus, comprises arefrigerating system and an evaporative cooling system.

Refrigerating system The refrigerating system comprises a coolingsection I l,'a compressor section I2, and an evaporative condensersection l3 as in conventional refrigerating systems. Air is forced intothe space I!) by a blower l4 operated by a prime mover, such as .anelectric motor I5. The air is drawn through a duct H5 in which isdisposed a cooling coil H which is maintained at a low temperature bythe evaporationof a refrigerating gas, such as ammonia'or Freon: Heat isabsorbed by the refrig- 5. crating gas from the air drawn past thecooling coil l1 and the temperature of the air forced into space I islowered. A certain amount of the water vapor contained in the air iscondensed on cooling coil El and drains into drain pan I3. Removal ofthis water vapor dehumidifies the air forced into space H) and rendersair condi-- tions more comfortable for human occupants of space W.

The evaporated refrigerating gas is compressed by the compressor l9which is driven by a prime mover, such as an electric motor 2|]. Thecompressed refrigerant gas then moves to the condenser coil 21 where theheat of compression and the latent heat of condensation are removed byevaporative cooling and the refrigerant gas is liquefied. Condenser coil2| is disposed in an air duct 22 and is cooled by the evaporation ofwater sprayed over coil 2| by a water pump 23 through a spraying means,such as a spray pipe 24. Air is moved from the outdoors 25 pastcompressor l9, compressor motor Zil, and condenser coil 2| to remove theheat emitted by motor 20, compressor l9, and the heat of compression andcondensation of the refrigerating gas in condenser coil 2|. After movingpast condenser coil 2|, the air is humid as well as warm since a portionof the water sprayed over condenser coil 2| is evaporated upon coming incontact with the warm condenser coil 2 l. The air is moved through duct22 and out into the outdoors 25 through an air duct 26 by condenserblower 21 driven by a prime mover, such as an electric motor 28.Electric motor 28 also drives water pump 23 which pumps water from pan29 which collects the water sprayed by spray pipe 24 which has not beenevaporated. Water may be supplied to pan 29 by any conventional means,not shown, so that water will always be present in pan 29.

It will be apparent that heat is extracted by the evaporatingrefrigerant gas in cooling coil H from the air moving through air ductIt into space H], the refrigerating gas then being compressed bycompressor [9 and liquefied in condenser coil 2|. The heat extracted bythe evaporating refrigerant gas in cooling coil I1 is released by therefrigerant gas in condenser coil 2| to the air moving past condensercoil 2| and is passed to the outdoors with the air moving through duct26. The degree of cooling of the air moving through duct It depends onthe amount of refrigerating ga allowed to evaporate in cooling coil I!per unit of time and this depends in turn on the amount of the liquefiedrefrigerating gas allowed to flow from condenser coil 2i to theexpansion valve 3% where the liquefled refrigerant gas evaporates, coolsin evaporating, and passes into the cooling coil In order to maintain apredetermined temperature in space H], the flow of liquefiedrefrigerating gas to expansion valve 30 is controlled by a conventionalsolenoid valve 3| which is controlled by a thermostat 32 located inspace It. If the temperature of the space H! tends to rise, thermostat32 will cause solenoid valve 3| to allow more liquefied refrigerant gasto pass to expansion valve 30, more heat will be absorbed from the airassing through duct is, and the temperature of the air in space Ii! willbe lowered.

Operation of compressor motor 28 is controlled by a low pressure switch33 and a high pressure switch 34 for automatically maintaining properrefrigerating gas pressures in cooling coil I7 and condenser coil 2|.Compressor motor 23 is started automatically Whenever the pressure ofpredetermined value and is stopped whenever the pressure in the coolingcoil I! falls below a D determined value or whenever the pressure of therefrigerant gas in condenser coil 2| exceeds a certain predeterminedvalue. Switches 33 and 34 insure that a sufficient amount of therefrigerant gas is always in a liquid state and also prevent thebuilding up of an excessively high pressure in condenser coil 2| and anexcessively high or excessively low pressure in cooling coil 11.

As shown in Figures 1 and 2, all the air moved past cooling coil I! maybe drawn from the outdoors 25 through ducts 35 and 35a or part of theair may be moved from the outdoors 25 through duct 35 and part of theair may be moved from space H] through duct 36. The position ofrecirculation damper 31 determines whether'only fresh air from theoutdoors is moved into space I!) or whether a portion of the air inspace 10 is recirculated through duct 36. In the position ofrecirculation damper 31 shown in Figures 1 and 2, both fresh air andrecirculated air is being moved into space It. A damper 31a providedwith a handle 31b may be provided in duct 35a to close duct 35a when nofresh air and only recirculated air is to be moved into space Hi. Thismay be desired when the outdoor air i intensely hot to avoid excessiveoperation of the refrigerating system. Damper 31 is moved by anysuitable prime mover such as electric damper motor 38 which may belinked to damper 31 in any conventional manner such as the sprocket andchain means 38a illustrated in Figure 2.

It will be noted that duct 36 is roughly four times the size of duct 35in cross section. This disparity in size causes the air moved byconditioner blower I4 to be about percent recirculated air and about 20percent fresh air when damper 3'! is positioned to allow a minimum offresh air to be moved into space H]. This ratio of recirculated air tofresh air is usually employed in operation of refrigerating systems forair conditioning.

Evaporatz'ue cooling system The evaporative cooling system of my airconditioning apparatus makes use of air duct 2 water pump 23 and spraypipe 24, condenser blower 21, and motor 28 of the refrigerating system.If the condenser coil 2| is not heated by the action of therefrigerating gas compressed by compressor l9, air moved by condenserblower 21 through the water spray caused by spray pipe 24 is cooled bythe evaporation of the sprayed water since the evaporating water absorbsheat from the air. In order to move the air cooled by the'wa-f ter sprayproduced by spray pipe 24 into space I0, I provide a condenser damper3'9 and an air duct 40 communicating with space I0 and also with duct22, when damper 39 is moved to the broken line position 4| of Figure 1.Condenser damper 39 is actuated by any suitable prime mover such aselectric damper motor 42 and is linked to motor 32 by any conventionalmeans, such as the sprocket and chain means 42a. Damper motors 38 and s2are of the geared-down type conventionally employed for this purpose andwill move their respective dampers 31 and 39 in either directiondepending on the manner in which their controls are operated. Dampermotors 38 and 42 will move the dampers 3! and 39 until the dampers arestopped by obstructions such as stops 42b. Condenser damper 39 isactuated by any suitable prime mover, such as electric damper motor.42:. and is linkedto motor 42- by-any con-; ventional-meanssuch as thesprocket and chain means 42a.

In operation of the air conditioning apparatus, it -is desirable thatthe refrigerating system functiorronly when the dry bulb temperature ofthe outdoor air exceeds a predetermined value, say 85 degreesFahrenheit.It is also desirable that it functionv even when the dry bulbtemperature is 85 degrees or less if the wet bulb temperature of theoutside air, which is an indication of the humid condition of the air,exceeds a certain predetermined value, say '79 degrees Fahrenheit.Thermostat 43 and 44a responsive to dry bulb temperatureand a thermostat44 responsive to wet bulb temperature are positioned to measure theoutside dry and wet bulb temperatures. Thermostats 32, 43, 44, 44a and45a are employed tov control automatically the operation of the airconditioningapparatus and a detailed description of. their associatedcontrols will be given later.

If it is desired to maintain a temperature of '75 degrees'in space H!and the outside temperature is below 75 degrees, it is not necessary tocool the air introduced into space 10 but a certain circulation of airis necessary to maintain comfortable conditions within space It. Aselector switch 45 may be employedto cause only conditioner motor IE torun. .Since the temperature of the outdoorair is below 75 degrees, amaximum of recirculated air and a minimum of the cold outdoor air mustbe moved through air duct to. The automatic control associated withthermostat 450. cause damper motor 38 to move recirculation damper 31 tothe position shown in Figure 1.

When the dry bulb temperature of the outside air is higher than 75degrees but not higher than 85 degrees Fahrenheit and its wet bulbtemperature islessthan 79 degrees, the evaporative coolingsystem isplaced in operation by the automatic controls. Damper motors 38 and 42move dampers 31 and 39 into the broken line positions 46'and 4|,respectively, and motors l5 and 28 are energized. No recirculated air isallowed to move through air duct 36, fresh outdoor air only movingthrough ducts I6 and 40 into space it. Since compressor motor 20 isnot energized, the air moving through duct 6 is not cooled. The onlycooling taking place is by evaporation of water in air duct 22. Duringthis phase of the operation of the air conditioning apparatus, a maximumvolume of .air is moved into and through space Hi sinceboth blowers l4and 2'! are moving air into space I0.

When. the outdoor dry. bulb temperature exceeds85 degrees or the wetbulb temperature exceeds'79 degrees the refrigerating system isautomatically brought into operation. Compressor motor 20 is energizedand compressor l9 begins to compress the refrigerant gas, the coolingcoil I! therefore causes the air moving through air duct 16 tobe cooled.At the same time damper motors 3B nd 42 are energized and move dampers3'land 39, respectively, to the solid line positions illustrated inFigure 1. A maximum amount of air is recirculated through air duct 36and the air. moved by blower 21 is moved outdoors through duct 26, thisair now being warm and moist due to the heat it has absorbed in passingpast condenser coil 2|. Thermostat 32 now controls solenoid valve 31 tocontrol the degree to Whichthe :air flowingthrough air duct 16 iscooled.

If the dryqbulb temperature of the'outdoor air now falls .1 belowdegrees while. the wet bulb temperature is lower than 79' degrees, motor20 is deenergized and motors 38 and 42 are energized to move dampers 31and 39 to the dashed line positions 46 and 4|, respectively, theenergization of the damper motor 42 is delayed by.

the action of thermostat 45a, however, to allow the water in pan 29 tocool to 79 degrees to avoid motor Hand to preclude-damage to damper 39,

condenser blower2l-is stopped each time damper 39 i moved.

Figure 2 illustrates diagrammatically an actual installation of the airconditioning apparatus illustrated schematically in Figure 1. Theapparatus is located in a small room 41 adjacent air conditioned space10. Air ducts 35, 35a and 26 lead directly to the outdoors. Duct 2B isso lo cated that the air it discharges cannot find its way into airducts 35 and 35a since the air discharged by. duct 26 is warmer and morehumid than the outdoor air. Fresh air is brought in through ducts 35 and35a' and flows through the cooling coil l7, through conditioner blower[4, here shown as discharging into duct which leads into space H). Thepath of flow of the fresh air is indicated by lines 50, 5!, and 52. Therecirculated air flows through duct 36, cooling coil ll, conditionerblower l4, and duct 48. The path of flow of the recirculated airisindicated by lines 53, 5e and 55. The combined flow of fresh andrecirculated air is indicated by lines 55 and 51. The air employed tocool the condenser coil 2| when the refrigerating system is in operationflows in through a window 58 or other aperture in room 47, and movesthrough grill 59 of the air conditioning pparatus past compressor 19,compressor motor 20, condenser coil 2|, spray pipe 24, through condenserblower 21, and to the outdoors through duct 26. The path of flow of thiair is indicated by line 60. When the evaporative cooling system is inoperation, this air follows the same path except that condenser damper39 blocks duct 26 and allows the air to flow through duct 40 into spaceIn.

Automatic. control system In order to obtain maximum efiicienoy ofoper-' ation of my air conditioning apparatus under varying conditionsof temperature and humidity Ihave provided an automatic control systemto operate the various components of my apparatus.

The conditioner motor l5, the compressor motor 23, and the condensermotor 28 are connected in parallel across a four wire three phase supplycircuit having leads 6!, 62, 63 and a neutral lead 64. Starting'contactors 65, 66, and 61 are provided for motors l5, 20 and 28respectively.

Contactor 65 comprises contacts 68, Hand [0 which connect motor [5 toleads '63, 6| and 62, respectively when the actuating coil II ofcontactor '65 is energized to start motor I5. An auxiliary contact 12,whose function will be described below, is also actuated simultaneouslywith contacts-68, 69 and 10 when actuating coil II is energized.C'ontactor B5 is provided with a conventional thermal overload relaywhich comprises heater coils I3 and I4 connected in series with contacts69 and I respectively, when the latter are in their actuated positions.The heater coils I3 and I4 allow the thermal overload contact I5 to openthe circuit of actuating coil it when excessive currents are drawn byconditioner motor I5. Since the contact I5 opens the circuit of coil II,coil II is deenergized and contacts 68, 69 and I0 return to thenon-actuated positions illustrated in Figure 3 and contitioner motor I5is stopped.

Contactor 61 similarly comprises three contacts TI, 18 and 19 whichconnect condenser motor 28 to leads 63, BI and 92, respectively when theactuating coil 80 is energized to start motor 28. An auxiliary contactSI, whose function will be described below, is also actuatedsimultaneously with contacts ll, I8 and I9 when actuating coil 80 isenergized. C-ontactor 6! is also provided with a conventional thermaloverload relay comprising heater coils 82 and 83 connected in serieswith contacts I8 and I9, respectively, when the latter are in theiractuated positions. Heater coils B2 and 03 operate thermal overloadcontact 84 to open the circuit of actuating coil 89 and stop condensermotor 28 when condenser motor 28 draws currents of overload intensity.

Contactor 65 similarly comprises three contacts 85, 86 and 81 whichconnect compressor motor 29 to leads 63, BI and 62 respectively, whenthe actuating coil 88 is energized to start compressor motor 20. Anauxiliary contact 89, whose function will be described below, is alsoactuated simultaneously with contacts 85, 86 and 97 when actuating coil89 is energized. Contactor E8 is also provided with a conventionalthermal overload relay comprising heater coils 99 and 9|, connected inseries with contacts 86 and 81, respectively, when the latter are intheir actuated positions. Heater coils 86 and 81 operate thermaloverload contact 93 to open the circuit of actuating coil 80 and stopcompressor motor 20 when compressor motor 20 begins to draw current ofoverload value.

In order to provide automatic operation of the air conditioningapparatus, I provide thermostats 32, 43 and 44a which are responsive totemperatures of air as measured by a dry bulb thermometer and which willbe referred to hereinafter as dry bulb thermostats to distinguish themfrom thermostat 44 which is responsive to the temperature of air asmeasured by a wet bulb thermometer and which will be referred tohereinafter as a wet bulb thermostat. I also provide a thermostat 45alocated in the water pan 29 and responsive to the temperature of thewater in pan 29. Thermostat 32 is preferably located at a position inspace I0 where it will be exposed to air having a temperature equal tothe average temperature of the air within space I0.

It is sometimes desirable to run only the conditioner blower I4 tomaintain a certain circulation of air within the air conditioned spaceI0 without cooling any air. At other times it may be desired to runeither solely therefrigerating system or the evaporativ-e cooling systemof my apparatus. Lastly, it is usually desirable to operate either therefrigerating system or the evaporative cooling system as dictated bythe temperature and humidity conditions of the outdoor air and to havethe change from one system to the other made automatically.

,In order to allow a choice to be made of any of the above four methodsof operating the air conditioning apparatus, I provide a four positionerate; when in position B, either the refrigerating system or theevaporative cooling system will operate, the automatic controlsdictating' the choice of the system to operate; when in position C,solely the evaporative cooling system will function, and when inposition D, solely the refrigerating system will function.

A double pole single throw toggle switch 9-4 is located adjacentselector switch 45 and must be closed before the air conditioningapparatus will operate. In addition, a time clock which operates acontact 96 may be used to insure that the air conditioning apparatuswill operate only during a stated period of the day, for example between8:00 a. m. and 5:00 p. m. During this period time clock 95 will maintaincontact 96 in actuated position connecting relay winding 91. acrossleads 6| and 53 through conductors 99 to I04. When relay winding 91 isenergized it moves contacts I55 and I06 to their actuated positionsconnecting conductors I01 and I08 to conductors I09 and 99,respectively.

Conditioner blower only operation Assuming now that time clock 95 hasmoved contact 96 to actuated position, that as a result contacts I05 andI06 are in their actuated positions, and that selector switch 45 is in Aposition to permit the operation only of conditioner blow er I4, closingof toggle switch 94 will connect contactor coil TI across leads 6| and63 through conductors I02, II9, III, thermal overload contact 75,conductor I09, contact I05, conductor I0'I, blade I I2 of toggle switch94, and conductors I08, 99, I00, and IOI. Since contactor coil 'II isenergized, contacts 68, 69, I0 and I2 are actuated and conditioner motorI5 now operates to drive conditioner blower I4.

It is desirable that a minimum of fresh air be brought in from theoutdoors when the outdoor temperature i below 75 degrees in order toprevent the air in space It from becoming toocold. Conditioner damper 31must, therefore; be brought to the position shown in Figure 1 in orderto allow a maximum of air to be drawn from space I0 and recirculatedthrough air ducts 36 and I9 back into space I0. Damper motor 38 isconnected across neutral lead 64 and lead 63 through conductors IOI,I00, contact I2, and conductors H3, H4 and H5 at the same time motor I5is connected across leads BI, 62 and 63. Damper motor 38 is controlledby conductors H6 and III which causes damper 31 to move to the positionshown in Figure 1 when they are short circuited by contact I I8 ofthermostat 44a. Since the thermostat 440. short circuits conductors II6and II? when the outdoor temperature is below '75 degrees, damper 3'5will always be in the position shown in Figure 1 when the outdoortemperature is below 75 degrees, allowing maximum recirculation of theair from space I0 and allowing a minimum of fresh air to be brought intospace I0 from the outdoors 25.

' At the same time that actuator coil II is energized, the coil IIQ ofcircuit breaker relay I20 is also energized since it is connected acrossleads 63 and 6| through conductors I00 and 99, contact I06, conductorI98, blade I2I of switch 94, conductor I22, the rotary contact I23 ofselector switch 45 and conductor I24. When coil H9 is energized, contactI25 disconnects conductors I26 and I2? so that conductors II! and H6will not be short circuited when contact II8 of thermo' Damper controlsThe control circuit of damper motor '42 are closely associated with thecontrol circuits of damper motor '38 and they will be described inconjunction with the description of damper motor 38. Damper motor 42,like damper motor 38, is connected across neutral lead 64 and lead 63when actuating coil 1| is energized. Damper motor 42 is connected acrossleads 64 and 63 through conductor I00, contact 12, and conductors '4,I28 and I29. Damper motor 42 is controlled by conductors I21 and I30.Damper 39 is "moved to the position indicated in Figure 1 whenconductors I21 and I30 are short circuite'd either by the contact I 3|of damper position relay I32 or by the contact I33 of thermostat 45a.When the outdoor temperature is above '15 degrees, contact IIB ofthermostat 44a connects conductor II1 to conductor I26. If at the sametime contact I25 of circuit breaker relay I20 i in its non-actuatedposition, conductors I21 and I26 are also connected. Since conductors H6and I30 are permanently connected at common connection I34, the controlconductors H6 and H1, and I21 and I30 of damper motors 3 8 and 42,respectively, are connected in parallel. The internal resistance of eachdamper motor 38 or 42 being relatively great, neither acts as a shortcircuit for the control conductors of the other. Contacts I3| and I33,therefore, short circuit both control conductors II 6 and I I1 andconductors I21 and I30 when either is moved to its actuated position andboth dampers 31 and 39 are moved to the dashed line positions 46 and 4|,respectively, shown in Figure 1. In this position damper 31 will notpermit air'to be recirculated from space I0. Damper 39, when in 'theposition 4 I will direct the air moved by blower 21 into space I0. Itwill be noted that both dampers 31 and 39 will be moved simultaneouslyexcept when the outdoor temperature is less than '75 degrees or contactI25 of relay I20'is in its actuated position.

The actuating coil I35 of damper position relay I32 is connected acrossthe solenoid coil I36 of the solenoid valve 3| to insure that damper 31will be in position to allow a maximum recirculation of air to space I0,and to insure that damper 39 'will be in position to divert all airmoving past condenser coil 2| to the outdoors when the refrigeratingsystem will of necessity be in operation since actuation of solenoidcoil I36 will allow refrigerant gas to enter cooling coil I1 and lowpressure switch 33 will cause compressor motor 20 to operate. In orderto avoid operationof damper motors "38 and 42 each time the solenoidcoil I36 is energized, thermostat 45a is placed in Water pan 29. As longas the temperature'of the "Water in pan 29 is above 79 degrees, contactI33 will remain in its actuated position connecting conductors I21 andI30 and dampers 31 and 39will remain in the positions shown in Figure 1.The period during which the solenoid coil is not energized should bemade short enough that the refrigerating system will operate againbefore the water in pan 29 cool below 79 degrees. Thewater inipan29"willthen be sprayed over cdnden'se'rcoil z'rana again heated by thecompressed and liquefying refrigerant gas. However, if the water in pan29 should cool to less than '19 degrees before solenoid coil I36 isagain energized, dampers 31 and 39 will move to positions shown bydashed lines 46 and 4|, respectively, and a moments delay will occurbetween the time solenoid coil I36 is again energized and the timecompressor I9 again is operated by motor "20. This delay is caused byswitch I31 whose function will'be described presently.

If damper 39 is moved from one position to another while condenser motor28 and condenser blower 21 are in operation, the movement of damper 39is impeded by the pressure of the air driven by blower 21. A largedamper motor 42 Will have to be employed to overcome this pressure andinsure smooth movement of damper 39. I provide a damper position switchI 31 which deenergizes contactor coil of starting contactor 61 and stopscondenser motor 28 and blower 2| each time damper 39 changes position.Switch I31 is provided with a pivoted blade I38 having an insulated endI39 engaging damper 39. At the initiation of movement of damper 39,insulated end I39 is engaged by damper 39 causing blade I38 to open thecircuit of contactor coil 80 by disconnecting conductor I40 fromconductor I41. As damper 39 approaches the end of its travel, conductorsI40 and I4'I "are again connected by blade I38 and contactor coil 80 isagain energized to start condenser motor 28 and operate condenser blower'21. Since actuator coil 88 of compressor motor 20 is energized throughcon? tact 8| of starter contactor 61, operation of compressor I9 is alsointerrupted or delay each time damper 39 changes its position.

Condenser and compressor control The condenser motor 28 and thecompressor motor 20 are controlled through their starting contactors 61and 66, respectively, by low pressure relay 33 which is opened when thepressure in the cooling coil I 1 falls below a predetermined value andwhich is closed when the pressure in cooling coil I1 rises above apredetermined value, a high pressure relay 34 which is normally closedand Which is opened when the pressure in condenser coil 2| reaches apredetermined high value, a single pole relay I42, and damper positionswitch I31.

The actuating coil 80 of condenser motor 28 is connected across leads 63and 6| through thermal overload contact 84, conductor I40, blade I38 ofdamper position switch I31 when damper 39 is in either of its oppositepositions, conductors |4|, I43 and I44, contact I45 of relay I42 when itis in its actuated position, contact I46 of low pressure relay 33 whenit is in its actuated position, conductors I41 and. II3, contact 12 ofstarter contactor 65, and conductor I00. Contact I45 is actuated toclosed position when its actuating winding I53 is connected'across leads63 and 6| when contacts 12 and I46 are both closed through conductorsI00, contact- 12, and conductors H3 and I41. Condenser motor 28therefore operates whenever the pressure in cooling coil I1 rises toabove a predetermined value and contact I46 is actuated, provided thatdamper 39 is in either of its opposite positions.

When contactor coil is energized, it 'ac'tuates contact 8| of thestarting actuator 61 connecting contactor coil 88 across leads 6| and 63through conductor I46, thermal overload contact 93, conductor I49,"contac't'8l, contact I50 of highpressure 'relay3 4, contact "I46;conductors I41 and I' I3,

"13 contact I2 and conductor I00. Compressor motor 28 will thereforeoperate whenever conditioner motor I and condenser motor 28 operateprovided the low pressure relay contact I46 and the high pressure relaycontact I56 are both in closed positions.

t is desirable that the compressor motor continue to operate until it isturned oil? by the opening of contact I43 of the low pressure relay eventhough during its operation either toggle switch 9 3 or time clock 95contact 96 is opened to stop operation of the air conditioning apparatusin order to prevent a relatively high pressure in cooling coil I? whichmay lead to malfunctioning of the refrigerating system as will beexplained below. The contact 39 of contactor 66 connects contactor coilII of conditioner motor I5 across leads (H and 63 through conductors I5Iand I52, thermal overload contact "I5, and conductor III]. Theconditioner motor I5 and condenser motor 28 will therefore continue tooperate even though switch 94 or contact 96- is opened until the contactI 36 of low pressure switch 33 opens.

If the pressure in condenser coil 2| exceeds a predetermined value whilecontact M6 is still in its closed position, contact I56 of high pressureswitch 3 will open deenergizing contactor coil 88 and stoppingcompressor motor 26. Condenser motor 23, however, will continue tooperate so that condenser coil 2| will be cooled by the water sprayed bypump 23 and by the air blown by blower Z'l to reduce the pressure. Whenthe pressure falls below the predetermined value, contact I56 will closeagain and compressor motor 26 will also operate again until eithercontact I46 of the low pressure switch 33 or the contact I56 of the highpressure switch 36 will open.

When contact I66 of low pressure switch 33 opens, both compressor motor23 and condenser motor 28 are stopped since actuating winding I53 ofrelay I42 is deenergized and contact M5 is opened.

Refrigerating system operation only If the rotary blade I23 of selectorswitch 35 is moved to position D, only the refrigerating system willoperate. It is sometimes necessary to operate only the refrigeratingsystem even though the outdoor temperature conditions call for operationof the evaporative cooling system. This is true of peak human occupancyheat load conditions when an abnormally large amount of heat is releasedin space It. Such conditions exist occasionally in most air conditionedspaces.

When rotaryblade I23 is in position D, and switch 9 3 and contacts I65and I63 are maintained in their actuated positions by time clock 35 andits associated coil 97, conductors IEl'I and I68 are connected andcontactor coil TI is energized starting conditioner motor I5. Whenconditioner motor I5 is in operation, actuating coil 5 5 is connectedacross leads 63 and 6| through conductor I66, contact I2, conductor II3, thermal overload contact 93 and conductor I68. Contact I51 willtherefore be actuated and will connect conductors I53 and I59. Solenoidcoil I36 will then be connected across leads 63 and GI throughconductors I60 and 39, contact I36, conductor I66, switch blade I2I,conductor I22, switch blad I23, conductors I63 and IE9, contact I51, andconductors I58 and I6I. Actuating coil I35 of damper position relay I32will be energized simultaneously with the energization of solenoid coilI36 and dampers 39 and 31 will move to,ior remain in, the positionssuitable for operation of the refrigerating system, as shown in Figure1.

The energization of solenoid coil I36 opens solenoid valve 3| allowingthe refrigerant gas to enter cooling coil I1 and the pressure of therefrigerant gas in cooling coil I'I will therefore be raised. ContactI46 of low pressure relay 33 will therefore be actuated and condensermotor 28 and compressor motor 26 will begin to operate. All controlsother than low pressure switch 33 and high pressure switch I50 areby-passed by moving rotary switch blade I23 of the selector switch 65 toposition D. Condenser motor 26 and compressor motor 26 will therefore bestopped only if the pressure of the refrigerating gas in coolingcoil Hor in evaporative condenser coil 2I exceed predetermined values. Therefrigerating system of the air conditioning apparatus will thereforefunction until either time clock 95 opens contact 96, switch 94 isopened, or the ratary switch blade I23 of selector switch'I45 is movedfrom position D.

Evaporatioe cooling operation only The eficiency of the refrigeratingsystem may be seriously impaired at times by abnormal wind conditionswhich cause the warm and humid air discharged to the outdoors by duct 26to be returned to the condenser coil air duct 22and bythe mechanicalfailure of components of the refrigerating system. Slipping of the beltswhich link motor 26 to blower 2i and water pump 23, low water supply inwater pan 29, clogging of the filter screen usually provided in theintake of the water pump 23, clogging of the outlet apertures of spraypipe 24, and corrosion of condenser coil 2| are examples of mechanicalfailures which lower the elficiency of the refrigerating system. Untilthe wind conditions change or the malfunctioningcomponents of therefrigerating system are repaired it will be necessary to employ onlythe evaporative 0O01il'lg system of the air conditioning apparatus. Bymoving rotary switch blade I23 of selector switch to position C, onlythe evaporative cooling system will be allowed to operate.

With rotary switch blade I 23 in positionC and switch 9 3 as well ascontacts I65 and I66 in closed position, actuator coil II is connectedacross leads 6i and 63 and conditioner motor I5 is caused to operate. Atthe same time, actuatingcoiltfl is connected across leads 6i and 63through thermal overload contact 84, conductor MILswitch blade I38 ofrelay I31, conductorsIGI, I43, I62, I68, contact I66, and conductorsligand I66. Condenser motor 23 will therefore also be placed inoperation. The position of damper 31 will depend on the outdoortemperature asdetermined by thermostat 43a and on the temperature of thewater in pan 29 as detected by thermostat 45a. The position of damper 3?will be determined in the same manner as it is determined when therotary switch blade I23 is in position A and only the conditioner motorI5 is operated. Whenthe outdoor temperature is below 75 degrees,conductors H6 and Ill are connected by contact I.I8 of thermostat Ma,and damper 31 moves to or remains in the position shown in Figure 1 toper- .mit a minimum of fresh air and a maximum of recirculated air to bebrought into space II). When the outdoor temperature is 75-degrees orhigher, contact IIB connects conductors Ill and i216 and conductors I I6and I H will be connected only when contact I33 of thermostat 45a isactuated. Contact I33 willclose only when. the tem-.-

I seam-eaten, water in p'an' 2'9 'exceeds l 79 degrees. Wlien this'eonditioii occurs when the outdoor temperature is '7 5 degrees orhigher, dampers 31 a'nd 39 are moved' to theiposition shown in Figurel-since contactl33 will 'move to closed position short circuitingconductors I21 and I 30 and conductors I I6- and I I1. If thetemperature of theoutdoor airis less than 75 degrees only damper 39 willmove to theposition-shown in Figtire *1. The-normalposition ofdamper 39duri'n'gth'dtim'e rotary switch'blade I26 is in position D'i-sthat'indicated by the da'shed'line 4| of Figure 1. 'Condenser'blower'flwill therefore move freshair into space' I unless the temperature of-thewater' in pan 29 exceeds- '79 degrees.

It will be' notedthatwhen rotary switch blades I 23 is in eitherposition A or C, solenoid coil I36 cannot be energized. l-Io'wever, acertain amount of refrigerant gas will seep through the valves ofcompress'or I9 and through the solenoid valve 31 -into cooling coil I1.Moreover, some refrigerant gas which is dissolved in the oil alwayspresent to greater or lesser extent in cooling coil I1 will vaporizewhen the temperature of the cooling coil 'I1 rises. The refrigerant gaswill tend to collect in thecompressor as the pressure in-cooling'coil-I'I i'ncreases and will cause mal- "function ofcompressor I9. 'Inorderto avoid such malfunction, compressor motor 20 and condenser motor2-8will'be -allowed to operate-each time the pressure in cooling -coilI1 exceeds a predetermined valueand contact I46-of the'low pressureswitch 33 is actuated. Since solenoid valve 3| will-remain closed, thec'ompressor motor 29 will operate only-the 'very short time needed topump "the refrigerant 'gaswhich-has seeped into cooling'c'oilI1intocondenser (30112 I. Conditioner motor I5 will' operatecontinuously when rotary switch blade I23 is in position A orC so thatthe actuator-001188 of starting conductor 66 of ccmpressor motor "20will be connected across leads '6I and-63'each time contact I46 is movedto actuated position through conductor I 48, thermal overloadcontact 93,conductor I4I, contacts BI, I50and I46, conductors I41 and H3, contact12 and conductor I80. In this manner the pressure -of the refrigerantgasin coil I1 is-kept below a certain'predetermined value regardless ofthe position of rotary-switch blade I23 but the time 0f operation ofcompressor I9 is kept veryshort when -blade I23 is in positions A or Cin order to minimize as much as possible the periods ofcostlyopera'tionof compressor I9.

Automatic operation conditioner blower I4 will operate if the outdoor'dry bulb temperature is below 75 degrees and the temperature of the airin space I0 is below 75 degrees.

If we assume now that the outdoor temperature isbelow 7-5 degrees asdetermined by thermostat 441; ead the indoor temperature is below -75degrees, contact I63 of room thermostat -32 is 'in'itsopen position andcontact H8 ofthermostat 44a connects conductors H6 and H1 so that damper31 is moved to the position shown in Figure 1 closing off air duct 35aand opening air duct 36 to allow a maximum of air to berecir'culatedinto space I0 and to allow only a minimumof fresh'air to be moved intospace I0through air duct 35. At this time only conditioner motor I5 willbe' operating. If the dry bulb outdoor temperature remains below '75degrees' and the temperature in space I0 rises above '75 degrees,contact I63 of room thermostat 32 will move to its closed positionconnecting actuating coil across leads 6| and 63 through'the'rmaloverload contact 84, conductor I40, switch blade I 38 of switch I31,conductor I4I, contact I64 of *wet bulb thermostat 44, conductor I65,contact I66 of dry bulb thermostat 43, conductors I61 and I68, contactI63, conductor I69, switch blade I23, conductor I22, switch blade I2I,conductor I 08, contact I06, and conductors 99 and I 00, Condenser motor28 and condenser blower 21 will therefore operate moving air cooled bythe water sprayed by spray pipe 24 into space I0. Damper 39 will be inthe position shown bydashed line 4| of Figure 1 since both-contacts I3Iand I33 will-be in their open positions. When the temperature in spaceI0 falls below 75 degrees contact I63 will move into itsopenposition'and condenser motor 28 will stop operating.

-If the outdoor dry bulb temperature now rises above 75 degrees, butdoes not exceed degrees and the wet bulb temperature is below 79degrees, contacts I64 and I66 will maintain their positions but contactII8 will move to connect conductor II1 to I26 and cause damper motor 38to move damper 31 to the dashed'line position 46'of Figure 1 sinceconductors H6 and H1 will no longer be short circuited, both contact I3Iand contact I33 being open since solenoid coil I36 is not energized andthe water in pan 29 has a temperature lower than '79 degrees. If thetemperature in space I0- exceeds 75 degrees but does not exceed 85degrees, "the condenser motor '28'and condenser blower '21 will blow aircooled 'by the water sprayed by pipe 24 into space I0 since damper 39will be in the position indicated by dashed line 4|. Both blowers I4 and21 will now be moving fresh air from the outdoors into space I0 insuringa relatively great and continuous change of air in space I0. If thetemperature in space I0 should fall to '75 degrees, contact I63 willopen and condenser motor 28 and condenser blower 21 will ceaseoperating. The evaporative cooling system 'will therefore never permitthe temperature in space I0 to fall below '75 degrees as long as theoutdoor temperature is 75 degrees or above.

When the outdoor dry bulb temperature exceeds 85 deg'rees'and thetemperature in space I0 exceeds 75 degrees contact I66, will connectconductor I61 to conductor I10 at the same time breaking the connectionof conductors I65 and I61. Solenoid coil I36 will now be connectedacross leads 63 and 6I through conductors I00 and 99, contact I06,conductor I08, switch blade I2I, conductor I22, rotary switch blade I23,conductor I69, contact I63, conductors I68 and I61, contact I66,conductors I10 and I59, contact I51, and conductors I58 and I6I. At thesame time actuating 'coil I35 of damper position relay I32 is energizedshort circ'uiting conductors I21 and 'andcausingdafiipers -31 and '39 tomove to aessa'so 17' the positions shown in Figure 1. Damper3'l willallow a minimum of fresh air to enter space It and damper 39 will causeall air moved by condenser blower 21 to be blown outdoors. As soon asdamper 39 has terminated its movement condenser motor '28 and compressormotor 29 will begin to operate provided that contact I46 of low pressureswitch 33 is in its actuated position. Contact I46 will be in thisactuated position whenever solenoid coil I36 is energized since thepressure in cooling coil I1 will rise due to admission of refrigerantgas by solenoid valve 3|. When the temperature in space In falls below'75 degrees, contact I63 will move to its open position and solenoidcoil I36 will be de-.

energized. Solenoid valve 3| therefore closes and contact I3I of damperposition relay I32 moves to its open position. Dampers 31 and 39 do notmove, however, since the water in pan 29 has been raised in temperatureto more than 79 degrees by the heat absorbed from condenser coil ZI andcontact I33 of thermostat 45a will connect conductors I21 and I30. Thetemperature of the water will normally remain above .79 degrees duringthe operation of the refrigerating circuit. Should an abnormal conditionarise and allow the temperature of the water to fall below 79 degrees,dampers 31 and 39 will move to positions 46 and AI, respectively.

Upon the next energization of solenoid coil I36, the dampers 31 and 39will revert to their original positions. When solenoid coil I36 isdeenergized, condenser motor 28 and compressor motor will continue tooperate until the pressure in cooling coil I1 has been brought down bycompressor I9 and contact I of low pressure switch 33 moves toopenposition. When contact I46 moves to open position motors 28 and 2!]stop and remain inoperative until solenoid coil I36 is again energizedand contact I46 moves to closed position.

The refrigerating system will operate even when the outdoor dry bulbtemperature is below 85 degrees and contact I I6 does notconnectconductors I61 and I10 if the wet bulb temperature of the outdoorair is above '79 degrees. In this case, conductor I16 is connected toconductor I51 through contact I64 which move to the right when the wetbulb temperature rises above '19 degrees, conductor I65 and contact I66of thermostat 53 which is in its leftmost position since the dry bulbtemperature is below 85 degrees. Solenoid coil I36 will, therefore, beenergized if contact I63 of the room thermostat 32 is in its closedposition and the refrigerating system will be in operation even thoughthe dry bulb outdoor temperature is below 85 degrees. When the out doordry bulb temperature is 85 degrees or higher, the wet bulb thermostat 44does not exert any control over the energization of solenoid coil 236since conductors I61 and I10 are directly connected by contact I66 ofthermostat 43.

If the refrigerating system is in operation and the dry bulb outdoortemperature drops below 85 degrees while the wet bulb temperature isbelow '19 degrees and the temperaturein spaced II] is above '15 degrees,contact I66 breaks the connection between conductors I61 and I16 andsolenoid coil I36 and actuating coil I35 of damper position relay I32are deenergized. Compressor motor 26 will continue in operation untilcontact M6 of low pressure switch 33 moves to its open position anddeenergizes actuator coil 69 and actuating coil I53 of circuit breakerI42.-

18 Compressor motor 26 will stop but condenser motor 28 will remainunchanged even though contact I3I of damper position switch I32 will beopen because contact I33 of thermostat 45a will remain closed since thetemperature of the water in pan 29 will be above '79 degrees. Condensermotor 23 and condenser blower 21 will therefore continue to move airpast condenser coil 2I and to the outdoors until the temperature of thewater drops to 79 degrees or below. This insures that the air whichmoves past condenser coil 2i is expelled to the outdoors until thetemperature of the condenser coil ill and of the water ceases to heat orhumidify the air brought in from the outdoors. When the temperature ofthe water drops to 79 degrees or lower, due mainly to the evaporativecooling of the water sprayed by pipe 24 and movement of air caused byblower 21, contact I33 will move to open position and dampers 31 and 39will move to dotted line positions A6 and ii, respectively to allow amaximum of fresh air to be brought into space it. When damper 39 beginsto move it actuates switch I31 and will cause condenser motor 29 tocease operation until damper 39 reaches the position indicated by dashedline il. It will be understood that this interruption of operation ofcondenser motor.

28 will occur each time damper 39 moves from one position to the other.

The time lag between cessation of operation of the refrigeration systemand the commencement of operation of the evaporative cooling circuitallows the changeover to take place without an abrupt change intemperature within space It. During the period of operation of therefrigerating system the temperature of the air within space It ismaintained at '15 degrees. The outdoor temperature now falling slightlybelow degrees, the outdoor air which will be moved into space it byblower It will have a temperature of about 85 degrees which will cause atemperature change of aboutlO degrees, During the 10 to 20 minutesrequired for the changeover from operation of the refrigeration systemto operation of the evaporative cooling system, the conditioner blowerIt will continue to recirculate air and to introduce a certain amount ofoutdoor air having a temperature of about 85 degrees into space I9.While the refrigerant gas in cooling coil I1 will lower the temperatureof this air while the compressor I6 is operating even though solenoidvalve 3! is closed, the drop in temperature willdecrease with thepassage of {time from the closing of solenoid valve 3!. When dampers 31and 39 finally change their positions to allow maximum amounts of freshair to be brought infrom the outdoors, the temperature differentialbetween the outdoor air and the air in space 16 will be relativelysmall. In addition, the temperature of the water now having fallen to'19 degrees, the temperature of the air moved by blower 21 islowered byevaporative cooling decreasing'the temperature differential stillfurther. iChe change in temperature in space It will therefore berelatively gradual and the increased circulation of air in space id dueto the additional air now moved into space It by blower 21 willmaintainthe temperature and humidity conditions in space 56 comfortable to thehuman occupants.

Actuating winding I54 is energized when contactor coil 1! is energizedand remains energized as long as conditioner motor 55 is in opera tionexcept when thermal overload contact 93 of compressor motor 20 is openeddue to some malfunction of the refrigerating system. In the latterevent, contact I51 disconnects conductor I58 fromconductor I59 andsolenoid coil I35 will not be energized until contact 93 is again movedto closed position. When contact I51 is in its non-actuated position, itconnects conductors I59 and I62 and insures that the evaporative coolingsystem will function if rotary.

switch blade I23 is in either position B, C, or D. Since compressor I9is no longer operating, low pressure switch I46 will ordinarily closeand connect actuator coil 80 across leads 6| and 63 through contact 84,conductor I49, switch blade I38, conductors I4I, I43, I62, and I44,contacts I45, I46, conductors I41 and H3, contact 12 and conductors I90and IIII. Dampers 31 and 39 will remain in their positions until thetemperature of the water in pan 29 drops below 19 degrees when contactI33 will move to its open position and dampers 31 and 39 will move topositions46 and 4|, respectively to allow a maximum of fresh air to bemoved into space I0. Contact I3I will be open whenever solenoid coil I35is deenergized and will therefore not prevent this movement of dampers31 and 39.

In many installations the air conditioning apparatus will be subjectedto a peak human occupancy heat load at night when the outdoortemperature and humidity conditions call for operation of theevaporative cooling system. In these installations a time clock I1I maybe employed to maintain a contact I12 in closed position throughout thepeak load period. When the contact I12 is in closed position anactuating.

and 63 coil I13 is connected across leads 6| through conductor I03,contact I12, and conductors I13a, I14, 99 and I08. Coil I13 closes a-contact I which connects conductors I61 and [.10 to bypass or shuntthermostat 43 when rotary switch blade I23 is in position B. Solenoidcoil I36 is connected across leads BI and 63 through conductors I6I andI58, contacts I51 and I15, conductors I15 and I68, contact I53 when thetemperature in space I9 is above '75 degrees, conductor I69, switchblade I23, conductor I-22, switch blade I2 I, conductor I08, contactI06, and conductors 99 and I09. Since solenoid coil I35 will beenergized whenever contact I63 moves to closed position, therefrigerating system will be in operation regardless of the outdoortemperature. Time clock I1I may be connected across leads 6| and 64through conductors I03 and I11.

In the above description, the varying thermostats were described asoperating when certain specific temperatures of air or water obtained.It will be obvious that these thermostats maybe set to operate whenpredetermined values of temperature of the air or water are reached. Theoptimum temperature values at which the thermostats should be set may beobtained empirically for each installation of the air conditioningapparatus.

An important advantage of my new and improved air conditioning apparatusis its 'versatility of operation which permits use of differentcomponents of the apparatus to meet the demands placed on the apparatusby variations in both internal and external conditions. The selectorswitch 45 allows operation of conditioner blower I4 by itself, theindependent operation of either the refrigerating system or theevaporative cooling system, and theautomatic operation of either therefrigerating system or the evaporativecooling system as the externaland internal conditions reach or fail to reach predetermined con ditionsof temperature and humidity. V

Another important advantage of the airconditioning apparatus is itseconomy of operation which restricts the relatively costly operation ofthe refrigerating systems to the periods when only refrigerative coolingwill insure comfortable conditions of temperature and humidity and whichemploys the relatively inexpensive evaporative cooling system at alltimes when evaporative cooling of the air will provide comfortabletemperature and humidity conditions in space I 9.

A further advantage of my air conditioning apparatus is that it providesa cooling system for use when the refrigerating systembecomesinoperative due to mechanical failures. If the condenser motor 28and water pump 23 are in operative condition, the evaporative coolingsystem may be employed during the period when the refrigerating systemis being restored to operative condition so that some cooling of the airin space It can always be provided.

Figure 4 illustrates a modified form of the air conditioning apparatus.For clarity of explanation, the components. of the apparatus illustratedin Figures 1 and 4 have been given like reference numerals. In themodified form of the air conditioning apparatus illustrated in Figure4.2.11 of the air moved by the conditioner blower I 4'is drawn from theconditioned space I 0 through the duct 36, the ducts 35 and 35a and thedampers 31 and i31a. of the apparatus ofFigure 1 not being provided. Insuch installation, the fresh air needed for mixing with the recirculatedair from the air conditioned space is drawn through the door 200 or thewindow 21H, of the space III. The damper 39 is shown provided with ahandle 292 for manual operation although a damper motor can be providedas in the previously described embodiment. The electrical circuitdiagram has not been'illustrated since any'circuit which will providefor selectively operating both the condenser blower 21 and theconditioner blower I4 when the refrigerating apparatus is keptinoperative is satisfactory. Manual switches may be used instead of theautomatic temperature controlled switches previously described.

In operation, when the outdoor air temperature exceeds a certainvpredetermined temperature, the refrigerating apparatus is turned on andair is moved by the conditioner blower from the conditioned space I 0through the duct 36 over the cooling coils I1 for cooling and back intothe conditioned space. Fresh air is admitted to the conditioned spacethrough the door 200 which is usually opened periodically as peopleenter the conditioned space or through a window 29I which may be openedto any desired degree. During such operation, the damper39- is in thesolid line position and the air driven by the condenser blower 21 aftermoving past the compressor I 9, compressor motor 20, condenser coil 2|is expelled through the duct 26 to the outdoors. This is theconventional operating method of refrigerating air conditioningapparatus.

When the temperature falls below a predetermined temperature, therefrigerating system is stopped by conventional controls so that norefrigerant gas is admitted into the cooling coils I1. The conditionerblower and the condenser blower are allowed to continue to operate butthe damper 39 is moved to the broken line position so that the air drawnby the condenser blower from the outdoors through the window 53 is movedinto the conditioned space through the duct 40 thus increasing greatlythe rate of flow of air into the conditioned space. This air will becooled by the evaporation of water sprayed by the spray pipe 24 over thecondenser coils 2!.

If the temperature and humidity conditions are suitable, it may bedesired merely to increase the rate of flow of fresh air into the airconditioned space without cooling any portion of the air by evaporativecooling. This may be accomplished by disconnecting the water pump 23, ineither of the two embodiments of the invention, from the motor 28 byslipping off the pulley belt driving the water pump. Of course, othertransmission devices may be employed if desired. For example, a clutchof any conventional type may be 'connected between the water pump andthe motor 28 to facilitate the disconnection of the water pump from itsdriving means.

Figure illustrates still another modified form of the air conditioningapparatus. For clarity of explanation, similar components of theapparatuses illustrated in Figures 1 and 5 have been given likereference numerals. In the modified form of the air conditioningapparatus illustrated in Figure 5, the cooling coil [1, the condensercoil Zl, the conditioner blower M, the condenser blower 2i and themotors to drive these elements, and all other elements of therefrigerating apparatus are contained in the housing 330. The housing360 has a grill in one end, not shown in Figure 1, which is similar tothe grill 59 shown in Figure 1, through which air is drawn by thecondenser blower 21 into the housing from the room 33! in which thehousing is located. Fresh air from the outdoors can move into the room3M through a window or grill 302 in the wall 333 of the building. U

A register 364 connecting the housing 300and the wall 335 separating theroom 33! from the conditioned space H) is provided with adjustablelouvers 398 which may be opened or closed to either permit or preventair to be drawn from the conditioned space H! by the conditioner blowerl4 over the cooling coil I! and back into the conditioned space Itthrough the duct 48 which is shown provided with a plurality ofregisters 30'! disposed in the conditioned space I0.

The register 3% is also provided with a plurality of adjustable louvers308 which may be opened or closed to either permit or prevent air to bedrawn from the room 3M by the conditioner blower I! and back into theconditioned space I0 through the duct 48. The register 394 is old in theart and, therefore, the details of its construction are not described.Suflice it to say that the louvers 306 and 338 maybe closed or opened toany desired degree by suitable control handles on the sides of theregister hidden in the drawing. In this installation, fresh air neededfor mixing with the recirculated air from the air conditioned space isdrawn from the outdoors through the register 302 in the wall 333 intothe room 30!,

from the room 30l between the louvers 338 into,

the register 30 i, and thence into the housing 398.

In operation, when the outdoor air temperature exceeds a certainpredetermined temperature, the refrigerating apparatus is turned on andair is moved by the conditioner blower from the conditioned spacebetween the louvers 336, which are in at least partly open position,through the reg-f.

ister 33 3 over the cooling coils I! in the housing 300 for cooling andback into the conditioned space through the duct 48. Fresh air is drawnfrom the room 33 I, which communicate with the 22 outdoors through theregister 302, between the louvers 308, which are also in at least partlyopen position, through the register 3% into the housing 3%, over thecooling coil I? and then into the conditioned space through the duct 48.The doorway 309 is closed, of course, by a door, not shown, duringoperation of the apparatus. During such operation, the damper is in theposition shown and the air moved by the condenser blower 2'7 from theroom 30! over the various heat producing elements of the refrigeratingapparatus and the condenser coil 2! is expelled to the outdoors throughthe duct 26. This is the conventional operating method of refrigeratingair conditioning apparatus. The outlet of duct 28 may be so positionedthat none of the warm air it conducts is likely to move back into theroom 3! through the register 332.

When the temperature falls below a predetermined temperature. therefrigerating system is stopped by any suitable controls so that norefrigerant gas is admitted into the cooling coil. The louvers 386 aremoved into closed position so that recirculation of air from theconditioned space I0 is stopped. The conditioner blower and thecondenser blower are allowed to continue to operate but the damper 39 ismoved by means of the handle 39 to a position in which it closes theduct 23 and opens the duct 40, so that air drawn by the condenser blowerfrom the outdoors through the register 332 into the housing 330 througha grill, not shown, since it is located in a side of the housing hiddenin Figure 5, and through the duct 4!! into the conditioned space thusgreatly increasing the rate of flow of air into the conditioned space.The air moved by the condenser blower will be cooled by the evaporationof water sprayed over the condenser coil of the refrigerating apparatus.As in the previously described forms of the invention, the waterspraying of the condenser coil can be stopped by disconnecting the waterpump from the motor which drives it.

While I have illustrated and described preferred embodiments of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications ma be made without departing from the spiritand scope of my invention and I, therefore, aim in the appended claimsto cover all such changes and modifications as fall within the truespirit and scope of my invention.

What is claimed is:

1. In an air conditioning apparatus: a refrigerating system comprising apair of heat exchangeelements, a first duct means communicating with aconditioned space, a second duct means communicating with the outdooratmosphere, a first damper means for closing oil said first duct means,a first blower means for drawing air from said conditioned space throughsaid first duct means and from the outdoor atmosphere through saidsecond duct means to form a primary mixture, said first blower meansmoving said primary mixture over one of said heat exchange elements andinto said conditioned space, said primary mixture being cooled in itspassage over said one of said heat exchange elements, spray means forspraying water over the other of said heat exchange elements, a secondblower means for drawing air from the outdoor atmosphere over the otherof said heat exchange elements, and a third duct means communicatingwith the outdoor atmosphere for moving the air drawn by second blowermeans back to the outdoor atmosphere; an evaporative cooling systemcomprising said second blower means, said spray means, and a fouith ductmeans for moving the air drawn by said second blower means from theoutdoor atmosphere and through the water sprayed by said spray means tosaid conditioned space; and second damper means closing oif said thirdduct means when in one position and closing off said fourth duct meanswhen in a second position, said first andthird duct means being openwhen said refrigerating system is in operation and being closed whensaid evaporative cooling system is in operation, said first and secondblower means operating during the operation of said evaporative coolingsystem and during the operation of said refrigerating system.

2. In the air conditioning apparatus of claim 1: a first motor means foroperating said first damper means; a second motor means for operatingsaid second damper means; and means responsive to the temperature andhumidity conditions of the outdoor atmosphere for placing saidrefrigerating system in operation when predetermined values oftemperature and humidity of the outdoor atmosphere are exceeded and forplacing said evaporating cooling system in operation when saidpredetermined values are not exceeded, said last mentioned meanscontrolling said first and second motor means to close said first andthird duct means when said evaporative cooling system is placed inoperation and to open said first and third duct means when saidrefrigerating system is placed in operation.

3. In the air conditioning apparatus of claim 2: means responsive to thetemperature of the water sprayed by said spray means and associated withsaid second motor means for closing said fourth duct means when thetemperature of said water exceeds a predetermined value.

4. In the air conditioning apparatus of claim 3: means responsive to themovement of said second damper means for stopping operation of saidsecond blower means when said second damper means is being moved fromone position to another.

5. In an air conditioning apparatus: a refrigerating system comprising apair of heat exchange elements, a first duct means communicating with aconditioned space, a second duct means communicating with the outdooratmosphere, a first damper means for closing off said first duct means,a first blower means for drawing air from said conditioned space throughsaid first duct means and from the outdoor atmosphere through saidsecond duct means'to form a primary mixture, said first blower meansmoving said primary mixture over one of said heat exchange elements andinto said conditioned space, said primary mixture being cooled in itspassage over said one'of said heat exchange elements, spray means forspraying water over the other of said heat exchange elements, a secondblower means for drawing air from the outdoor atmosphere over the otherof said heat exchange elements, and a third duct means communicatingwith the outdoor atmosphere for moving the air drawn by second blowermeans back to the outdoor atmosphere; an evaporative cooling systemcomprising said second blower means, said spray means, and a fourth ductmeans for moving'the air drawn by said second blower means through thewater sprayed by said. spray means to saidcon'ditioned space; seconddamper. means associated with said third and 24' fourth duct means, saidsecond damper means: closing off said third duct means when in oneposition and closing 01? said fourth duct means when in a secondposition, said first and third duct means being open when saidrefrigerating system is in operation and being closed when saidevaporative cooling system is in operation, said first blower meansoperating during the operation of said evaporative cooling system andduring the operation of said refrigerating system; a first motor meansfor operating said first damper means, a second motor means foroperating said second damper means, and means responsive to thetemperature and humidity conditions of the outdoor atmosphere forplacing said refrigerating system in operation when predetermined valuesof temperature and humidity of the outdoor atmosphere are exceeded andfor placing said evaporating cooling system in operation when saidpredetermined values are not exceeded, said last mentioned meanscontrolling said first and second motor means to close s'aid first andthird duct means when said evaporative cooling system is placed inoperation and to open said first and third duct" means when saidrefrigerating system is placed in operation; and means responsive to themove ment of said second damper means for stopping operation of saidsecond blower means when said damper means is being moved from oneposition to another.

6. In an air conditioning apparatus, a refrigcrating system comprising apair of heat ex change elements, a first duct means communicating with aconditioned space, a second duct means communicating with the outdooratmosphere, a first damper means for closing off said first duct means,a first blower means for drawing air from said conditioned space throughsaid first duct means and from the outdoor atmosphere through saidsecond duct means to form a primary mixture, said first blower meansmoving said primary mixture over one of said heat ex change elements andinto said conditioned space, said primary mixture being cooled in itspassage over said one of said heat exchange elements, spray means forspraying water over the other of said heat exchange elements, a secondblower means for drawing air from the outdoor atmosphere over the otherof said heat exchange elements, and a third duct means communicatingwith the outdoor atmosphere for moving the air drawn by second blowermeans back to the out door atmosphere; an evaporative cooling systemcomprising said second blower means, said spray means, and a fourth ductmeans for moving the air drawn by said second blower means through thewater sprayed by said spray means to said conditioned space; seconddamper means associated with said third and fourth duct means, saidsecond damper means closing off said third duct means when in oneposition and closing off said fourth duct means when in a secondposition, said first and third duct means being open when saidrefrigerating system is in operation and being closed when saidevaporative cooling system is in operation, said first blower meansoperating during the operation of said evaporative cooling system andduring the operation of said refrigerating. system; a first motor meansfor operating said first damper means; a second motor means foroperating said second damper means; and means responsive to thetemperature and humidity conditions of the out-- doorzatmosphereforplacing said refrigerating.

system in operation when predetermined values of temperature andhumidity of the outdoor atmosphere are exceeded and for placing saidevaporating cooling system in operation when said predetermined valuesare not exceeded, said last mentioned means controlling said first andsecond motor means to close said first and third duct means when saidevaporative cooling system is placed in operation and to open said firstand third duct means when said refrigerating system is placed inoperation; and means responsive to the temperature of the outdooratmosphere and associated with said first motor means to move said firstdamper means to open said first duct means when the temperature of theoutdoor atmosphere falls below a predetermined low value and to movesaid first damper means to close said first duct means when thetemperature of the outdoor atmosphere rises above said predetermined lowvalue temperature.

7. The air conditioning apparatus of claim 6: and means responsive tothe temperature of the air within said conditioned space for arrestingoperation of said second blower means when the temperature of the airwithin said conditioned space falls below a predetermined low value andfor starting operation of said second blower means when the temperatureof the air within said conditioned space rises above said predeterminedlow value.

8. The air conditioning apparatus of claim 1: and manually operatedswitch means operatively associated with said refrigerating andevaporative cooling systems for permitting selective choice of operationof either of said systems.

9. The air conditioning apparatus of claim 1: and automatic controlmeans operatively associated with said refrigerating and evaporativecooling systems and responsive to predetermined temperature and humidityconditions of the outdoor atmosphere for selectively operating either ofsaid systems. i

10. The air conditioning apparatus of claim 9: and manually operatedswitch means operatively associated with said refrigerating andevaporative cooling systems and said automatic control means forpermitting automatic and manually selective choice of operation ofeither of said systems.

11. In an air conditioning apparatus: a refrigerating system comprisinga cooling 'coil a condenser coil, compressor means connected betweensaid coils for exhausing a refrigerant gas from said cooling coil intosaid condenser coil. valve means between said condenser coil and saidcooling coil for controlling the flow of said refrigerant gas from saidcondenser coil to said cooling coil, a first duct means communicatingwith a conditioned space, a second duct means communicating with theoutdoor atmosphere, a first damper means having two operative positionsassociated with said first and second duct means, said first dampermeans closing off said first duct means when in one of said twooperative positions and opening said first duct means when in the otherof said two operative positions, a first blower means for moving airpast said cooling coil, said first blower means circulating air fromsaid conditioned space and from said outdoor atmosphere over saidcooling coil and into said conditioned space when said first damper isin one of said two operative positions, said first blower meanscirculating air only from the outdoor atmosphere over said cooling coiland into said conditioned space when said first damper means is in theother of said two operative conditions, said air being cooled in passingover said cooling coil when said valve means permits refrigerant gas tomove from said condenser coil to said cooling coil, means for sprayingwater over said condenser coil, a second blower means for drawing airfrom the outdoor atmosphere over said condenser coil, and a third airduct means communicating with the outdoor atmosphere for moving airdrawn from the outside atmosphere by said second blower means back tosaid outdoor atmosphere; an evaporative cooling system comprising saidsecond blower means, said water spray means, and a fourth air duct meanscommunicating with said conditioned space for moving air moved by saidsecond blower means through the water sprayed over said condenser coilinto said conditioned space; and a second damper means having twooperative positions operatively associated with said third and fourthduct means, said second damper means closing said third duct means whenin one of said two operative positions and closing said fourth ductmeans when in the other of said two operative conditions, said firstdamper means being in said other of its two operative positions and saidsecond damper means being in said one of its two operative positionswhen said refrigerating system is in operation, said first damper meansbeing in said one of its two operative positions and said second dampermeans being in said other of its two operative positions when saidevaporative cooling system is in operation.

12. In the air conditioning apparatus of claim 11: a first motor meansfor operating said first damper means, a second motor means foroperating said second damper means; and means responsive topredetermined conditions of temperature and humidity of the outdooratmosphere for maintaining said refrigerating system in operation whenthe temperature and humidity of the outdoor atmosphere exceedpredetermined values and for maintaining said evaporative cooling systemin operation when the temperature and humidity of the outdoor air do notexceed said predetermined values, said last mentioned means controllingsaid first and second motor means to close said first and third ductmeans and open said fourth duct means when said evaporative coolingsystem is in operation and to open said first and third duct means andclose said fourth duct means when said refrigerating system is inoperation.

13. In the air conditioning apparatus of claim 12: means responsive tothe temperature of the water sprayed by said spray means and operativelyassociated with said second motor means for closing said fourth ductmeans when the temperature of said water exceeds a predetermined value.

14. In the air conditioning apparatus of claim 13: means responsive tothe movement of said second damper means for stopping operation of saidsecond blower means when said second damper means is being moved by saidsecond motor means from one of its two operative positions to the other.

15. In the air conditioning apparatus of claim 14: means operativelyassociated with said compressor and said first and second motor meansfor placing said evaporative cooling system in operation when saidcompressor fails to function when the temperature and humidity of theoutdoor temperature exceeds said predetermined values.

16. In an air conditioning apparatus: a refrigerating system comprisinga cooling coil, a condenser coil, compressor means connected betweensaid coils for exhausing a refrigerant gas from said cooling coil intosaid condenser coil, valve means between said condenser coil and saidcooling coil for controlling the flow of said refrigerant gas from saidcondenser coil to said cooling coil, a first duct means communicatingwith a conditioned space, a second duct means communicating with theoutdoor atmosphere, a first damper means having two operative positionsassociated with said first and second duct means, said first dampermeans closing off's'aid first duct means when in one of said twooperative positions and opening said first duct means when in the otherof said two operative positions, a first blower means for moving airpast said cooling coil, said first blower means circulating air fromsaid conditioned space and from said outdoor atmosphere oversaid'cooling coil and into said conditioned space when said first dampermeans is in said one of said two operative positions, said first blowermeans circulating air only from the outdoor atmosphere over said coolingcoil and into said conditioned space when said first damper means is inthe other of said two operative conditions, said air being cooled inpassing over said cooling coil when said valve means permits refrigerantgas to move from said condenser coil to said cooling coil, means forspraying water over said condenser coil, a second blower means fordrawing air from the outdoor atmosphere over said condenser coil, and athird air duct means communicating with the outdoor atmosphere formoving air drawn'from the outside atmosphere by said second blower meansback to said outdoor atmosphere; an evaporative cooling systemcomprising said second blower means, said water spray means, and afourth air duct means communicating with said conditioned space formoving air drawn by said second blower means into said conditionedspace; and a second damper means having two operative positionsoperatively associated with said third and fourth duct means, saidsecond damper means closing said third duct means when in one of saidtwo operative positions and closing said fourth duct means when in theother of said two operative conditions, 'said'first damper means beingin said other of its two operative positions and said second dampermeans being in said one of its two operative positions when saidevaporative cooling system is in operation, said first damper meansbeing in said one of its two operative positions, said second dampermeans being in said other of its two operative positions when saidrefrigerating system is in operation, a first motor means for operatingsaid first damper means, a second motor means for operating said seconddamper means; and means responsive to predetermined conditions oftemperature and humidity of the outdoor atmosphere for main-- tainingsaid refrigerating system in operation when the temperature and humidityof the outdoor temperature exceed predetermined values and formaintaining said evaporative cooling system in operation when thetemperature and humidity of the outdoor air do not exceed saidpredetermined values, said last mentioned means controlling said firstand second motor means to close said first and third duct means and opensaid fourth duct means when said evaporative cooling system is inoperation and to open said first and third duct means and close saidfourth duct means when said refrigerating system is 28 operation; andmeans responsive to the move ment of said second damper means forstopping operation of said second blower means when said second dampermeans is being moved by said second motor means from one of its twooperative positions to the other.

17. In an air conditioning apparatus: a refrigerating system comprisinga cooling coil, a condenser coil, a compressor means connected betweensaid coils for exhausting a refrigerant gas from said cooling coil intosaid condenser coil, valve means between said condenser coil and saidcooling coil for controlling the fiow of said refrigerant gas from saidcondenser coil to said cooling coil, a first duct means communicatingwith a conditioned space, a second duct means communicating with theoutdoor atmosphere, a first damper means having two operative positionsassociated with said first and second duct means, said first dampermeans closing ofi said first duct means when in one of said twooperative positions and opening said first duct means when in the otherof said two operative positions, a first blower means for moving airpast said cooling coil, said first blower means circulating air fromsaid conditioned and from said outdoor atmosphere over said cooling coiland into said conditioned space when said first damper means is in saidother of said two operative positions, said first blower meanscirculating air only from the outdoor atmosphere over said cooling coiland into said conditioned space when said first damper means is in saidone of said two opera tive conditions, said air being cooled in passingover said cooling coil when said valve means permits refrigerant gas tomove from said condenser coil to said cooling coil, means for sprayingwater over said condenser coil, a second blower means for drawing airfrom the outdoor atmosphere over said condenser coil, and a third airduct means communicating with the outdoor atmosphere for moving airdrawn from the outside atmosphere by said second blower means back tosaid outdoor atmosphere; an evaporative cooling system comprising saidsecond blower means, said water'pump means, and a fourth air duct meanscommunicating with said conditioned space for moving air drawn by saidsecond blower means into said conditioned space; a second damper meanshaving two operative positions operatively associated with said thirdand fourth duct means, said second damper means closing said third ductmeans when in one of said two operative positions and closing saidfourth duct means when in the other of said two operative positions,said first damper means being in said other of its two operativepositions and said second damper means being in said one of its twooperative positions when said evaporative cooling system is inoperation, said first damper means being in said one of its twooperative positions and said second damper means being in said other ofits two operative positions when said refrigerating system is inoperation; a first motor means for operating said first damper means; asecond motor means for operating said second damper means; and meansresponsive to predetermined conditions of temperature and humidity ofthe outdoor atmosphere for maintaining said refrigerating system inoperation when the temperature and humidity of the outdoor atmosphereexceeds predetermined values and for maintaining said evaporativecooling system in operation when the temperature and humidity of theoutdoor air do not exceed'said predetermined values, said last mentionedmeans controlling said first and second motor means to close said firstand third duct means and open said fourth duct means when saidev-aporative cooling system is in opera-- tion and to open said firstand third duct means and close said fourth duct means when saidrefrigerating system is in operation; and means operatively associatedwith said first motor means responsive to the temperature of the outdoorair and operative when said evaporative cooling system is in operationto move said first damper means to open said first duct means when thetemperature of the outdoor atmosphere falls below a predetermined lowvalue and to close said first duct means when the temperature of theoutdoor atmosphere rises above said predetermined low value.

18. The air conditioning apparatus of claim 1'7: and means responsive tothe temperature of the air within said conditioned space and operativewhen said evaporative cooling system is in operation for arrestingoperation of said second blower means when the temperature of the airwithin said conditioned space falls below a predetermined low value andfor starting operation of said second blower means when the temperatureof the air within said conditioned space falls below a predetermined lowvalue and for starting operation of said second blower means when thetemperature of the air within said conditioned space rises above saidlast mentioned predetermined low value.

19. The air conditioning apparatus of claim 11: and manually operatedswitch means operatively associated with said refrigerating andevaporative cooling systems for permitting selective choice of operationof either of said systems.

20. The air conditioning apparatus of claim ll: and automatic controlmeans operatively associated with said refrigerating and evaporativecooling system and responsive to predetermined temperature and humidityconditions of the outdoor atmosphere for selectively operating either ofsaid systems.

21. The air conditioning apparatus of claim 9:

and manually operated switch means operatively associated with saidrefrigerating and evaporative cooling system and said automatic controlmeans for permitting automatic and manually selective choice ofoperation of either of said systems.

22. In the air conditioning apparatus of claim 11: and pressureresponsive switch means connected between said cooling coil and saidcompressor and operatively associated with said compressor formaintaining said compressor in operation when the pressure of saidrefrigerant in said cooling coil exceeds a predetermined value.

23. In an air conditioning apparatus: a refrigerating system comprisinga pair of heat exchange units, a first blower means for moving air overone of said heat exchange units and into a conditioned space, said airbeing cooled in moving over said one of said heat exchange units, acooling means for removing heat from the other of said heat exchangeunits comprising a second blower means and a water spray means, saidwater spray means forming a water spray over said other of said exchangeunits, said second blower means moving air from the outdoor atmosphereover said other of said heat exchange units and back to the outdooratmosphere; and an evaporative cooling system comprising said spraymeans, said second blower, and means for directing the air moved by saidsecond blower 30 means from the outdoor atmosphere through said waterspray to said conditioned space when said evaporative cooling system isin operation, said first blower means being in operation during theoperation of said refrigerating system and said evaporative coolingsystem.

. .24. The air conditioning apparatus of claim 23: and manually operablemeans for selectively placing either of said systems in operation.

25. The air conditioning apparatus of claim 23: and automatic controlmeans responsive to predetermined values of temperature and humidity ofthe outdoor air for selective operation of either of said systems.

.26. In an air conditioning apparatus: a refrigerating system comprisinga pair of heat exchange units, a first blower means for moving air froma conditioned space and from the outdoor atmosphere over one of saidheat exchange units and into said conditioned space, said air beingcooled in moving over said one of said heat exchange units, a coolingmeans for removing heat from the other of said heat exchange unitscomprising a second blower means and a water spray means, said waterspray means forming a water spray over said other of said heat exchangeunits, said second blower moving air from the outdoor atmosphere oversaid other of said heat exchange units and back to the outdooratmosphere; and an evaporative cooling system comprising said spraymeans, said second blower, and means for directing the air moved by saidsecond blower from the outdoor atmosphere through said water spray tosaid conditioned space when said evaporative cooling system is inoperation; and means operatively associated with said first blower forallowing said first blower to move air from the prising a second blowerfor moving air from the outdoor atmosphere over said other of said heatexchange units and back to the outdoor atmosphere; and means forincreasing the volume of air moved from the outdoor atmosphere into saidconditioned space when said refrigerating system is not in operation,said last mentioned means including said second blower and means fordirecting the air moved by said second blower from the outdooratmosphere into said conditioned space.

28. In an air conditioning apparatus: a refrigerating system comprisinga pair of heat exchange units, a first blower means for moving air froma conditioned space and from the outdoor atmosphere over one of saidheat exchange units and into said conditioned space, said air beingcooled in moving over said one of said heat exchange units, a coolingmeans for removing heat from the other of said heat exchange unitscomprising a second blower for moving air from the outdoor atmosphereover said other of said heat exchange units and back to the outdooratmosphere; and means for increasing the volume of air moved from theoutdoor atmosphere into said conditioned space when said refrigeratingsystem is not in operation, said last mentioned

